Laser drivers are used to drive laser diodes within various types of information recording/reproducing apparatuses, such as DVD and CD drives, DVD camcorders, and DVD video recorders. Typically, a laser driver provides a current to a laser diode, causing the laser diode to output a light signal. The light signal is appropriately focused by an optical system (e.g., including lenses, prisms and splitters) before the light signal irradiates an optical media disk. The magnitude of the current provided by the laser driver (which controls the output power of the laser diode) may vary depending on whether the laser diode is being used to read data from or write data to the media. Further, the magnitude of the current may also depend on specific disc media, DVD or CD standards, and/or the speed at which data is being read or written.
Environmental variations (such as temperature variations) and aging of the laser diode may affect the characteristics (e.g., threshold current and slope efficiency) of the laser diode. Accordingly, there is a need to accurately control the power of a laser diode to compensate for changes in the laser diode's characteristics.
Conventionally, a laser driver is located on an optical pickup, which is connected to a main circuit board through a flex cable that allows for analog communications between the main circuit board and the laser driver. Typically, a chip that performs Automatic Power Control (APC) and Running Optical Power Control (ROPC) is located on the main circuit board. Accordingly, the chip including the APC and ROPC typically must send and receive serial signals over the flex cable in order to communicate with and control the laser driver. When such signals must travel the relatively long distance up and down the flex cable, these signals often pick up noise or distortion prior to reaching their destination. It would be beneficial to improve on the convention systems in order to overcome some, and preferably all, of the above mentioned disadvantages.